I’ve got my site almost figured out, just a couple things I need help with

1. Edit style.css and change the color code to #fff in:

#footer a, #footer a:link, #footer li a:visited {
border-bottom:0 none;
color:#333333;
text-decoration:none;
}

2. Edit header.php and look for wp_page_menu. Change the show_home parameter to 0.
https://codex.www.ads-software.com/Template_Tags/wp_page_menu

Also, I’d like to make buttons in the bar for the categories to replace the ones in the topics widget, if possible.

That could be difficult. What kind of buttons did you have in mind?

I want to more than one on the Categories pages and the Archives page

You’ll need a custom query to reset the number of post displayed in those templates. Edit category.php and archive.php and add:

<?php
$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
$args= array(
	'posts_per_page' => 3,
	'paged' => $paged
);
query_posts($args);
?>

just before the start of the Loop. If you don’t have a category.php template file. don’t worry. The archive.php template will be used for both types of pages.

I’d want to just list the titles of posts as links to the individual posts in both these places

That’s easily done. Just edit the template file(s) and remove all the post content – except the post title and its permalink – within the Loop. The following page will help you to identify the Loop:
https://codex.www.ads-software.com/The_Loop

Thanks for the help.

The font color change worked perfectly.
However, neither “wp_page_menu” nor “show_home” appeared in my header.php.

I figured a workaround for the buttons/categories issue, I think. I made pages for the category headings, and when I make a post in each one I’ll just update each page to include a include a link to that post. It’s not the most efficient way to do it, I’m sure, but it works.

I also don’t have category.php and archive.php. Is this weird?

Nevermind. I got it figured out.